Combination gaseous and liquid fuel burner



Dec. 23, 1958 R. a. WARNECKE COMBINATION GASEOUS AND LIQUID FUEL BURNER 2 Sheets-Sheet 1 Filed Nov. '7, 1952 IN V EN TOR.

Dec. 23, 1958 R. 1. WARNECKE 2,865,440

COMBINATION GASEOUS AND LIQUID FUEL BURNER Filed Nov. '7, 1952 2 Sheets-Sheet 2 IN VEN TOR.

United States Patent QOMBKWATION GASEOUS AND LiQUllD Robert 1. Warneci-te, Cheehtowaga, N. 11, assignor to itlohgrts flordon Appliance Corporation, ituifalo,

Application N ovemher 7 1952, Serial No. 319,261

1 Claim. (tCl. fill-11} This invention relates to combination oil and gas burner units particularly adapted for domestic, commercial or industrial heating purposes.

The desirability of burners of this type which can efficiently burn either liquid or gaseous fuel in a single unit has long been recognized and is particularly desirable where the supply of one type of fuel is at times limited, for example, during extremely cold weather conditions because of excessive demand for fuel. Generally the supply of gas is most subject to fluctuations in cold weather, and where the supply of gas is relied upon for heating under normal conditions it is very desirable to have a supply of oil available for use with the burner when peak loads on the gas occur. Combination oil and gas burners have heretofore been built at a sacrifice in efiiciency to either the gas or oil burner.

One of the objects of this invention is to provide a combination oil and gas burner with means of improved construction for supplying a mixture of gaseous fuel and air to the burner. Another object is to provide a burner of this kind with a mixing tube operating by atmospheric injection and through which a mixture of primary air and gas is supplied to a burner when the same is operating on gas and through which air flows to the burner when the same is operating on liquid fuel. A further object is to provide a burner of this type which can be easily and efficiently manufactured and in which the supply of gas and air to the burner can be readily adjusted. It is also another object of this invention to provide a combination burner with a gas burner which is so constructed as to provide for a thorough mixing of the gas with primary air and to reduce materially the tendency of the gas burner to flash back when the supply of gas to the same is interrupted.

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

in the accompanying drawings:

Fig. 1 is a side elevation of a combination gaseous and liquid fuel burner embodying this invention.

Fig. 2 is a fragmentary central sectional elevation thereof on an enlarged scale.

Fig. 3 is a rear elevation thereof.

Fig. 4 is a transverse sectional view thereof, on line 41- 5, Fig. 1.

In my improved combination burner as shown in the drawings by way of example, a gas burner is applied to an oil burner of standard and well known construction and, consequently, it is not deemed necessary to describe the oil burner in detail. This oil burner however is of the mechanical atomizing type which includes a tubular air duct formed to be inserted into a furnace into a position to discharge fuel and air into the combustion chamber. The air duct shown is of cylindrical form but may be of any other suitable cross sectional shape. The air duct is connected with a fan or blower 11 so that the required amount of air will be passed from the blower ice into the air duct 16. Within the air duct is an oil burner or nozzle 12 connected by means of a tube 13 to a pump 14 which discharges the oil or other liquid fuel through an oil control valve 15 and the pipe 13 to the burner 12. 16 represents the terminals of a high tension ignition de vice of any suitable type for igniting the fuel discharged from the oil burner nozzle 12. Air deflectors 17 and 18 are provided for producing a whirling motion of the air discharged from the duct 141 to provide for better mixing of air with the fuel. The oil burner may be supported adjacent to the furnace in any suitable or desired manner, for example, by means of an adjustable stand or support 19.

' The fan or blower 11 has an air inlet 20 which may be regulated as desired to control the amount of air passed by the blower to the air duct 10, the blower being driven by an electric motor 21. 22 represents a removable plate which, when removed, renders the interior of the air duct 11 and the parts mounted therein accessible. The oil pipe 13 is mounted on this plate and a tube 23 extends from the oil valve 15 to the plate 22 and is connected with the pipe 13 by a coupling 24, which may be disconnected from the oil pipe 13 when the plate 22 is to be removed. An oil burner of any other suitable conr struction may be employed, if desired.

in order to apply a gas burner to an oil burner, a sleeve or shell 25 is provided which extends about the air duct iii of the oil burner in spaced relation thereto. This sleeve may be made in two parts, the outer part 26 being made of a metal of greater resistance to damage by heat, such as stainless steel, and may be welded or otherwise secured to the sleeve 25 to form a part thereof. This sleeve extends throughout the greater portion of the length of the air duct 10 of the oil burner, and in the particular construction shown by way of example, the

extension 26 of the sleeve 25 extends somewhat beyond the oil burner air duct 10, and it will be noted that the space between the air duct 10 and sleeve 25 and its extension at their discharge end is unobstructed, so that a single port burner results.

The space between the air duct 10 and sleeve 25 constitutes a passage through which a primary mixture of air and gas flows to the discharge end of the burner.

In accordance with my invention, the inner end of the sleeve 25 is provided with a transverse wall 28 which closes this end of the discharge passage: 29 between the air duct 16) and the sleeve 25. A primary mixture of air and gas is discharged into this end of the discharge passage 29 from a mixing tube 30 which has an elbow or bent portion 31 which connects with the discharge passage 29. The mixing tube 30 is provided at the receiving end thereof with a flared or bell-shaped mouth 32 into which a jet of gas is discharged from a gas duct or nozzle 33 and the amount of gas discharged from the nozzle 33 into the bell-mouthed end 3 2 of the mixing tube may be controlled in any suitable manner, for example, by means of an adjustable orifice 35, as has heretofore been commonly used in connection with gas burners.

The amount of air passing to the mixing tube 30 may be controlled by means of an air shutter in the form of a disk which is adjustable lengthwise of the gas pipe or nozzle 33 toward and from the bell-mouth 32. Consequently, a jet of gas discharged into the bell-mouth of the mixing tube draws into the mixing tube by an injector or inspirator action a quantity of air for mixture with the gas .and the gas jet is directed axially into the mixing tube 3i), and consequently, acts to impart movement lengthwise of the mixing tube to the gas and air. The

, elbow or bent portion 31 is inclined toward the discharge end of the passage 29, so that the flow of. mixture in the mixing tube imparts movement of the mixture in the pasi sage toward the discharge end thereof. The mixing tube is preferably of a tapering or Venturi shape which facilitates the mixing of air and gas. This mixture than passes through the elbow portion Bill into the discharge passage 2% between the air duct lit) and the sleeve 25. In this discharge passage further mixing of the air and gas takes place, since the mixture on entering the passage 29 impinges against the air duct it), so that the mixture flows to a certain extent in a spiral direction or circuitous path in the passage 29.

In the particular construction shown, the mixing tube 30 extends in a direction substantially parallel to the discharge passage 29, but if desired the mixing tube 3% may be; arranged at an angle to this axis so that the primary mixture may be discharged into the passage 25? in a somewhat tangential direction, thus causing the mixture to travel in the discharge tube in a spiral or whirling path for further mixing of the air and gas.

Further mixing of the air and gas in the primary mixture, may be produced by means of'baffies 33 interposed between the air duct lib and the sleeve 25 and these bafiles 38 may also serve the purpose of further supporting the duct lltl and sleeve 25 in concentric relation to each other. The receiving end of themixing tube may be supported in any suitable manner, for example, by means of one or more supporting straps 39 mounted on part of the oil burner.

The primary mixture discharged from the passage may be ignited in any suitable or desired manner, for example, by means of a pilot burner 34 of any suitable or well known construction, the flame of which may also be controlled by suitable means heretofore employed in connection with gas burners. It will be noted that this pilot flame extends into the mixture of oil and air projected from the oil burner, and consequently, also serves to ignite the oil burner, thus supplementing the high tension ignition hereinbefore referred to.

The pilot burner and the accessories thereto are arranged in a channel 35which may be made of sheet metal welded or otherwise suitably secured to the sleeve These accessories may, for example, comprise an ignitor tube and a thermo-responsive "device which prevents opening of the gas control valve when the pilot becomes extinguished, but since these accessories are well known and have been used with gas burners, they are not herein described, particularly since they may be dispensed with or replaced'by pilot burner accessories of other construction. The combination burner construction described, however, is such that it-rnay be used with any controls or accessories heretofore applied to oil burners and gas burners when used separately. 7

The control .of gas to the pipe 33 may be effected in anysuitableor desired manner, for example, by means of a gas pressure regulator 4d and a gas valve ll, both of which are arranged on a pipe or duct d2 leading to the gas discharge pipe or nozzle 33 as shown in Fig. 3. lhe pressure regulator and gas valve are omitted from Fig. l for sake of clarity. Since these parts are'similar to corresponding parts heretofore used in connection with gas burners not combined with oil burners, no it ther description of the same nor of the electrical controls for operating them is deemed necessary. 44 represents a gas supply pipe leading to the pressure regulator 4i) and the supply of gas to the burner may be shut oft by means of a hand valve 45.

When gas is used as the fuel, the fan or blower ll is kept in operation and the supply of oil to the oil burner nozzle 12 is stopped. Consequently, secondary air to produce complete combustion of the gas in the primary mixture is supplied through the air duct lid to the gas flame. The operation of this fan may be controlled automatically so that the same ceases to operate when the supply of both gas and oil to the burner is stopped. it, however, there should be a failure of the supply of electric current to the motor 21 driving the blower it, then due to chimney draft and possibly to a slight extent to an injector action produced by the flow of. primary airand gas mixture through the passage 29, some flow of air through the air duct from the air inlet openings 26 in the tan housing will take place. This flow of air will, of course, be materially less than that produced by the fan or blower, and consequently, to produce complete com bustion of the gas, it is necessary to reduce the amount of primary mixture delivered to the burner. Gas valves such as shown at ll in Fig. 3 are usually provided with means or manually controlling the flow of gas through the same, this manual control being effected by turning a stem of the gas valve il. Hence by providing a reduced flow of gas to the mixer 3d and the passage 22 a satisfactory flame can be produced which is generally surTicient to maintain a comfortable temperature in a building normally heated by the combination burner.

The operation of the oil burner and gas burner may be controlled by means of the usual electrical controls ordinarily used with such burners when used separately from each other. Such automatic control systems are, however, preferably modified to the extent that the fan or blower is continued in operation when the operation of the oil burner is stopped, and. the burner Consequently, the apparatus for effecting this automatic control of the combination burner is not herein described, since it is, of course, also possible to operate each burner on the oil or gas cycle manually without such automatic controls.

The combination burner herein described incorporates the advantages of a single port burner over a multiport burner in that the burner shown offers less frictional resistance to the flow of gas and air mixture therethrough than multi-port burners, thus increasing the capacity of the single port burner. Furthermore, a single port burner is exceptionally silent in its operation and does not produce the flash back and resulting percussion noises on extinction of the flame, and this property is particularly enhanced because of thelength of travel of the mixture through the mixing tube and the discharge passage 29. The length of this travel also produces a very tho-rough mixing of the gas and primary air. The gas burner described provides alarge amount of flexibility in adjustment of the gas jet and primary mixture by means of the adjustable gas discharge orifice 35 and the air control shutter as. The single port burn-er described also has the advantage of presenting a very small surface area which is exposed to radiant heat developed in a combustion chamber during the op eration of either burner. The gas burner described produces an annular ribbon of flame which makes for a more uniform mixing of secondary air with the primary mixture than. in the case of multiple port burners, thus producing better combustion of the fuel.

By using an air injection type burner, the passage between the outer sleeve and the air duct is at all times open to the flow of air through the passage, even when the gas burner is not in operation. This has decided advantages. In the first place, it results in a cooling of the discharge end of the oil burner when the same is in operation, and in the second place, the pulsations which frequently occur in connection with oil burners are in many cases eliminated or materially reduced by supplying an extra quantity of air to the combustion chant-- her through this passage. Another advantage or providing an atmospheric injection type of gas burner is that it makes it possible to operate the gas burner when the supply of electric current to the burner is interrupted, since in that case, the gas burner can be used with a reduced quantity of gas, as has been described.

While I have shown only a single'mixing' tube 33, it will be obvious that two or more mixing tubes may be provided for discharging primary mixture to the discharge passage 29. I

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claim.

I claim as my invention:

A combination burner for both liquid and gaseous fuel comprising a liquid fuel burner having an air duct containing an atomizing nozzle adjacent to the outer end thereof but entirely contained therein and to which liquid fuel is supplied under pressure, a blower connected with said air duct for supplying air thereto, means for imparting a whirling motion to the air flowing in said duct, 21 metal sleeve extending about said air duct concentrically therewith and permanently secured to said air duct in spaced relation thereto and forming therewith a passage open at its outer end adjacent to the discharge end of said air duct, said passage being of substantially uniform cross-sectional area throughout the major part of its length with no portion thereof of substantially greater cross sectional area than at the discharge end thereof, the discharge end of said sleeve terminating short of the discharge end of said air duct and the other end of said sleeve being closed, a mixing tube connected with said sleeve adjacent to said other end of said sleeve and extending in a direction to discharge a primary mixture of air and gas into said passage in a direction toward the discharge end of said passage for producing further mixing of air and gas in said passage while moving toward the discharge end thereof, and means for admitting air and gas into said mixing tube in a direction to induce flow of said air and gas toward said passage.

References Cited in the file of this patent UNITED STATES PATENTS 319,865 Schutte Oct. 30, 1888 1,510,039 Canfield Sept. 30, 1924 1,797,570 Ferguson Mar. 24, 1931 1,986,796 De Florez Ian. 8, 1935 1,995,934 Mangold Mar. 26, 1935 2,333,531 Ferguson Nov. 2, 1943 2,518,025 Knight Aug. 8, 1950 2,590,948 Du Perow Apr. 1, 1952 FOREIGN PATENTS 878,243 France Oct. 5, 1942 257,416 Great Britain Sept. 2, 1926 

